bcm43xx_dma.c

无线网卡驱动,有很好的参考价值,在linux_2.6.21下可以直接使用,如果在其他平台,可以参考移植

err_destroy_tx0:
	bcm43xx_destroy_dmaring(dma->tx_ring0);
	dma->tx_ring0 = NULL;
no_dma:
#ifdef CONFIG_BCM43XX_PIO
	printk(KERN_WARNING PFX "DMA not supported on this device."
				" Falling back to PIO.\n");
	bcm->__using_pio = 1;
	return -ENOSYS;
#else
	printk(KERN_ERR PFX "FATAL: DMA not supported and PIO not configured. "
			    "Please recompile the driver with PIO support.\n");
	return -ENODEV;
#endif /* CONFIG_BCM43XX_PIO */
}

/* Generate a cookie for the TX header. */
static u16 generate_cookie(struct bcm43xx_dmaring *ring,
			   int slot)
{
	u16 cookie = 0x1000;

	/* Use the upper 4 bits of the cookie as
	 * DMA controller ID and store the slot number
	 * in the lower 12 bits.
	 * Note that the cookie must never be 0, as this
	 * is a special value used in RX path.
	 */
	switch (ring->index) {
	case 0:
		cookie = 0xA000;
		break;
	case 1:
		cookie = 0xB000;
		break;
	case 2:
		cookie = 0xC000;
		break;
	case 3:
		cookie = 0xD000;
		break;
	case 4:
		cookie = 0xE000;
		break;
	case 5:
		cookie = 0xF000;
		break;
	}
	assert(((u16)slot & 0xF000) == 0x0000);
	cookie |= (u16)slot;

	return cookie;
}

/* Inspect a cookie and find out to which controller/slot it belongs. */
static
struct bcm43xx_dmaring * parse_cookie(struct bcm43xx_private *bcm,
				      u16 cookie, int *slot)
{
	struct bcm43xx_dma *dma = bcm43xx_current_dma(bcm);
	struct bcm43xx_dmaring *ring = NULL;

	switch (cookie & 0xF000) {
	case 0xA000:
		ring = dma->tx_ring0;
		break;
	case 0xB000:
		ring = dma->tx_ring1;
		break;
	case 0xC000:
		ring = dma->tx_ring2;
		break;
	case 0xD000:
		ring = dma->tx_ring3;
		break;
	case 0xE000:
		ring = dma->tx_ring4;
		break;
	case 0xF000:
		ring = dma->tx_ring5;
		break;
	default:
		assert(0);
	}
	*slot = (cookie & 0x0FFF);
	assert(*slot >= 0 && *slot < ring->nr_slots);

	return ring;
}

static void dmacontroller_poke_tx(struct bcm43xx_dmaring *ring,
				  int slot)
{
	u16 offset;
	int descsize;

	/* Everything is ready to start. Buffers are DMA mapped and
	 * associated with slots.
	 * "slot" is the last slot of the new frame we want to transmit.
	 * Close your seat belts now, please.
	 */
	wmb();
	slot = next_slot(ring, slot);
	offset = (ring->dma64) ? BCM43xx_DMA64_TXINDEX : BCM43xx_DMA32_TXINDEX;
	descsize = (ring->dma64) ? sizeof(struct bcm43xx_dmadesc64)
		: sizeof(struct bcm43xx_dmadesc32);
	bcm43xx_dma_write(ring, offset,
			(u32)(slot * descsize));
}

static void dma_tx_fragment(struct bcm43xx_dmaring *ring,
			    struct sk_buff *skb,
			    u8 cur_frag)
{
	int slot;
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	dma_addr_t dmaaddr;
	struct sk_buff *bounce_skb;

	assert(skb_shinfo(skb)->nr_frags == 0);

	slot = request_slot(ring);
	desc = bcm43xx_dma_idx2desc(ring, slot, &meta);

	/* Add a device specific TX header. */
	assert(skb_headroom(skb) >= sizeof(struct bcm43xx_txhdr));
	/* Reserve enough headroom for the device tx header. */
	__skb_push(skb, sizeof(struct bcm43xx_txhdr));
	/* Now calculate and add the tx header.
	 * The tx header includes the PLCP header.
	 */
	bcm43xx_generate_txhdr(ring->bcm,
			       (struct bcm43xx_txhdr *)skb->data,
			       skb->data + sizeof(struct bcm43xx_txhdr),
			       skb->len - sizeof(struct bcm43xx_txhdr),
			       (cur_frag == 0),
			       generate_cookie(ring, slot));
	dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
	if (dma_mapping_error(dmaaddr) || dmaaddr + skb->len > ring->bcm->dma_mask) {
		/* chip cannot handle DMA to/from > 1GB, use bounce buffer (copied from b44 driver) */
		if (!dma_mapping_error(dmaaddr))
			unmap_descbuffer(ring, dmaaddr, skb->len, 1);
		bounce_skb = __dev_alloc_skb(skb->len, GFP_ATOMIC|GFP_DMA);
		if (!bounce_skb)
			return;
		dmaaddr = map_descbuffer(ring, bounce_skb->data, bounce_skb->len, 1);
		if (dma_mapping_error(dmaaddr) || dmaaddr + skb->len > ring->bcm->dma_mask) {
			if (!dma_mapping_error(dmaaddr))
				unmap_descbuffer(ring, dmaaddr, skb->len, 1);
			dev_kfree_skb_any(bounce_skb);
			assert(0);
			return;
		}
		memcpy(skb_put(bounce_skb, skb->len), skb->data, skb->len);
		dev_kfree_skb_any(skb);
		skb = bounce_skb;
	}

	meta->skb = skb;
	meta->dmaaddr = dmaaddr;

	fill_descriptor(ring, desc, dmaaddr,
			skb->len, 1, 1, 1);

	/* Now transfer the whole frame. */
	dmacontroller_poke_tx(ring, slot);
}

int bcm43xx_dma_tx(struct bcm43xx_private *bcm,
		   struct ieee80211_txb *txb)
{
	/* We just received a packet from the kernel network subsystem.
	 * Add headers and DMA map the memory. Poke
	 * the device to send the stuff.
	 * Note that this is called from atomic context.
	 */
	struct bcm43xx_dmaring *ring = bcm43xx_current_dma(bcm)->tx_ring1;
	u8 i;
	struct sk_buff *skb;

	assert(ring->tx);
	if (unlikely(free_slots(ring) < txb->nr_frags)) {
		/* The queue should be stopped,
		 * if we are low on free slots.
		 * If this ever triggers, we have to lower the suspend_mark.
		 */
		dprintkl(KERN_ERR PFX "Out of DMA descriptor slots!\n");
		return -ENOMEM;
	}

	for (i = 0; i < txb->nr_frags; i++) {
		skb = txb->fragments[i];
		/* Take skb from ieee80211_txb_free */
		txb->fragments[i] = NULL;
		dma_tx_fragment(ring, skb, i);
	}
	ieee80211_txb_free(txb);

	return 0;
}

void bcm43xx_dma_handle_xmitstatus(struct bcm43xx_private *bcm,
				   struct bcm43xx_xmitstatus *status)
{
	struct bcm43xx_dmaring *ring;
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	int is_last_fragment;
	int slot;
	u32 tmp;

	ring = parse_cookie(bcm, status->cookie, &slot);
	assert(ring);
	assert(ring->tx);
	while (1) {
		assert(slot >= 0 && slot < ring->nr_slots);
		desc = bcm43xx_dma_idx2desc(ring, slot, &meta);

		if (ring->dma64) {
			tmp = le32_to_cpu(desc->dma64.control0);
			is_last_fragment = !!(tmp & BCM43xx_DMA64_DCTL0_FRAMEEND);
		} else {
			tmp = le32_to_cpu(desc->dma32.control);
			is_last_fragment = !!(tmp & BCM43xx_DMA32_DCTL_FRAMEEND);
		}
		unmap_descbuffer(ring, meta->dmaaddr, meta->skb->len, 1);
		free_descriptor_buffer(ring, meta, 1);
		/* Everything belonging to the slot is unmapped
		 * and freed, so we can return it.
		 */
		return_slot(ring, slot);

		if (is_last_fragment)
			break;
		slot = next_slot(ring, slot);
	}
	bcm->stats.last_tx = jiffies;
}

static void dma_rx(struct bcm43xx_dmaring *ring,
		   int *slot)
{
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	struct bcm43xx_rxhdr *rxhdr;
	struct sk_buff *skb;
	u16 len;
	int err;
	dma_addr_t dmaaddr;

	desc = bcm43xx_dma_idx2desc(ring, *slot, &meta);

	sync_descbuffer_for_cpu(ring, meta->dmaaddr, ring->rx_buffersize);
	skb = meta->skb;

	if (ring->index == 3) {
		/* We received an xmit status. */
		struct bcm43xx_hwxmitstatus *hw = (struct bcm43xx_hwxmitstatus *)skb->data;
		struct bcm43xx_xmitstatus stat;
		int i = 0;

		stat.cookie = le16_to_cpu(hw->cookie);
		while (stat.cookie == 0) {
			if (unlikely(++i >= 10000)) {
				assert(0);
				break;
			}
			udelay(2);
			barrier();
			stat.cookie = le16_to_cpu(hw->cookie);
		}
		stat.flags = hw->flags;
		stat.cnt1 = hw->cnt1;
		stat.cnt2 = hw->cnt2;
		stat.seq = le16_to_cpu(hw->seq);
		stat.unknown = le16_to_cpu(hw->unknown);

		bcm43xx_debugfs_log_txstat(ring->bcm, &stat);
		bcm43xx_dma_handle_xmitstatus(ring->bcm, &stat);
		/* recycle the descriptor buffer. */
		sync_descbuffer_for_device(ring, meta->dmaaddr, ring->rx_buffersize);

		return;
	}
	rxhdr = (struct bcm43xx_rxhdr *)skb->data;
	len = le16_to_cpu(rxhdr->frame_length);
	if (len == 0) {
		int i = 0;

		do {
			udelay(2);
			barrier();
			len = le16_to_cpu(rxhdr->frame_length);
		} while (len == 0 && i++ < 5);
		if (unlikely(len == 0)) {
			/* recycle the descriptor buffer. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			goto drop;
		}
	}
	if (unlikely(len > ring->rx_buffersize)) {
		/* The data did not fit into one descriptor buffer
		 * and is split over multiple buffers.
		 * This should never happen, as we try to allocate buffers
		 * big enough. So simply ignore this packet.
		 */
		int cnt = 0;
		s32 tmp = len;

		while (1) {
			desc = bcm43xx_dma_idx2desc(ring, *slot, &meta);
			/* recycle the descriptor buffer. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			*slot = next_slot(ring, *slot);
			cnt++;
			tmp -= ring->rx_buffersize;
			if (tmp <= 0)
				break;
		}
		printkl(KERN_ERR PFX "DMA RX buffer too small "
			"(len: %u, buffer: %u, nr-dropped: %d)\n",
			len, ring->rx_buffersize, cnt);
		goto drop;
	}
	len -= IEEE80211_FCS_LEN;

	dmaaddr = meta->dmaaddr;
	err = setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC);
	if (unlikely(err)) {
		dprintkl(KERN_ERR PFX "DMA RX: setup_rx_descbuffer() failed\n");
		sync_descbuffer_for_device(ring, dmaaddr,
					   ring->rx_buffersize);
		goto drop;
	}

	unmap_descbuffer(ring, dmaaddr, ring->rx_buffersize, 0);
	skb_put(skb, len + ring->frameoffset);
	skb_pull(skb, ring->frameoffset);

	err = bcm43xx_rx(ring->bcm, skb, rxhdr);
	if (err) {
		dev_kfree_skb_irq(skb);
		goto drop;
	}

drop:
	return;
}

void bcm43xx_dma_rx(struct bcm43xx_dmaring *ring)
{
	u32 status;
	u16 descptr;
	int slot, current_slot;
#ifdef CONFIG_BCM43XX_DEBUG
	int used_slots = 0;
#endif

	assert(!ring->tx);
	if (ring->dma64) {
		status = bcm43xx_dma_read(ring, BCM43xx_DMA64_RXSTATUS);
		descptr = (status & BCM43xx_DMA64_RXSTATDPTR);
		current_slot = descptr / sizeof(struct bcm43xx_dmadesc64);
	} else {
		status = bcm43xx_dma_read(ring, BCM43xx_DMA32_RXSTATUS);
		descptr = (status & BCM43xx_DMA32_RXDPTR);
		current_slot = descptr / sizeof(struct bcm43xx_dmadesc32);
	}
	assert(current_slot >= 0 && current_slot < ring->nr_slots);

	slot = ring->current_slot;
	for ( ; slot != current_slot; slot = next_slot(ring, slot)) {
		dma_rx(ring, &slot);
#ifdef CONFIG_BCM43XX_DEBUG
		if (++used_slots > ring->max_used_slots)
			ring->max_used_slots = used_slots;
#endif
	}
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_RXINDEX,
				(u32)(slot * sizeof(struct bcm43xx_dmadesc64)));
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_RXINDEX,
				(u32)(slot * sizeof(struct bcm43xx_dmadesc32)));
	}
	ring->current_slot = slot;
}

void bcm43xx_dma_tx_suspend(struct bcm43xx_dmaring *ring)
{
	assert(ring->tx);
	bcm43xx_power_saving_ctl_bits(ring->bcm, -1, 1);
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA64_TXCTL)
				| BCM43xx_DMA64_TXSUSPEND);
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA32_TXCTL)
				| BCM43xx_DMA32_TXSUSPEND);
	}
}

void bcm43xx_dma_tx_resume(struct bcm43xx_dmaring *ring)
{
	assert(ring->tx);
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA64_TXCTL)
				& ~BCM43xx_DMA64_TXSUSPEND);
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA32_TXCTL)
				& ~BCM43xx_DMA32_TXSUSPEND);
	}
	bcm43xx_power_saving_ctl_bits(ring->bcm, -1, -1);
}